Glucose, Mannose and fructose give identical osazones. Explain

Explanation

The osazone formation involves the reaction at `C_(1) and C_(2)` carbon while the rest of the molecule remains intact. Since glucose and fructose differ from each other only in the arrangement of atoms `C_(1) and C_(2)` therefore, they give the same osazone as shown:
`{:(" "CHO),(" |"),(" "CHOH),(" |"),(" "(CHOH)_(3)),(" |"),(" "CH_(2)OH),(" Glucose"):}underset(underset(-NH_(3),-2H_(2)O)(-C_(6)H_(5)NH_(2),))overset(3C_(6)H_(5)NHNH_(2))rarr{:(" "CH=N NHC_(6)H_(5)),(" |"),(" "C=N NHC_(6)H_(6)H_(5)),(" |"),(" "(CHOH)_(3)),(" |"),(" "CH_(2)OH),(" Glucosazone"):}`
`{:(" C"H_(2)OH),(" |"),(" C=O"),(" |"),(("CHOH")(3)),(" |"),(" C"H(2)OH),("Fructose"):}undersetunderset(-NH_(3),-2H_(2)O)(-C_(6)H_(5)NH_(2))overset(3C_(6)H_(5)NHNH_(2))rarr{:(" CH"=N NHC_(6)H_(5)),(" |"),(" C"=N NHC_(6)H_(5)),(" |"),((CHOH)(3)),(" |"),((CH(2)OH)),("Fructosazone"):}`